Archive for the ‘Knee Anatomy’ Category
Joint Cartilage
Why does your doctor recommend exercise as a treatment option for your knee osteoarthritis?
Imagine the joint cartilage in your knee as a sponge on your kitchen sink. When you are young the sponge is brand new and able to absorb large quantities of water. Now think about the sponge on your sink that is well-used – it doesn’t absorb as much water as it used to, right?
Your knee is the same way. Joint cartilage is 90% water. The purpose of the other 10% is to retain that water to provide a cushion. By bending your joint (exercising) what you are doing is forcing the sponge inside your knee to absorb and release water. This keeps the cartilage hydrated and healthy.
Think about the forgotten sponge under the sink. It is dry, brittle and sad. It crumbles in your hands. Exercise will help keep your knee joints lubricated and happy.
chondrocyte
A chondrocyte is a cell found within cartilage. Chondrocytes are like small factories that produce collagen and proteoglycans – the main ingredients in the cartilaginous matrix.
Collagen is a thin, ropey protein that is the primary component of connective tissue.
Proteoglycans fill in the spaces between the collagen cells. Glucosamine and chondroitin help strengthen the cartilaginous matrix and help control knee osteoarthritis on the cellular level.
- articular capsule
The articular capsule or capsular ligament contains the knee cap, ligaments, bursae, and menisci. Also included is the synovial membrane and the fibrous membrane. These membranes are separated by fatty deposits in the front and back of the knee.
Injury or wear and tear to any of these components could lead to of affect your osteoarthritis.
knee meniscus
The menisci of the knee joint is a crescent-shaped cartilage structure that disperses friction in the knee joint. The knee menisci is flat on the bottom and concave on the top. The menisci of the knee is divided into two parts: medial (inside) and lateral (outside). Both sides of the menisci provide structural strength to the knee when tension and torsion are applied to it.
When the meniscus is injured doctors either repair it or remove part of it. It depends on where the tear is located, the age of the patient, and the skill of the doctor. Either a repair or removal of the meniscus can lead to osteoarthritis.
Bursa
A bursa is the fluid-filled sac that provides a cushion between the bones, tendons, and muscles surrounding a joint. This helps the knee move freely and protects the bones and cartilage. The knee bursa is filled with synovial fluid. Bursa is latin for “purse” because the fluid-filled sac looks a lot like a small purse.
Receiving an injection of synovial fluid is a treatment option for knee osteoarthritis.
Knee Cartilage
Cartilage is a slippery cushion-like tissue between your bones. It serves as a smooth, resilient cushion that allows your knee joint to move freely.
There are two types of joint cartilage in your knees: fibrous and hyaline.
1. Fibrous cartilage comprises the menisci, two pads of cartilage that disperse friction in between the lower leg and thigh. Acting like shock absorbers, it has tensile strength and can resist pressure.
2. Hyaline cartilage covers the bony surfaces that joints move along. Flexible and strong, its smooth surface is slippery. This allows the knee joint to move easily. Hyaline cartilage will wear over the years, and has a limited capacity for self-restoration.
Osteoarthritis occurs when the cartilage in your knee erodes.
Calf Muscles
Triceps Surae: The calf muscles are located beneath the knee on the back of your leg. They are responsible for lifting your foot so you can walk, run, and stand. There are two muscles that connect to the foot by means of the Achilles tendon:
- Gastrocnemius – Branches off into two heads that connect above the knee to the bottom of the femur.
- Soleus – Lies beneath a portion of the gastrocnemius and attaches to the top of the tibia.
A torn calf muscle can change the way your knee moves. This can lead to osteoarthritis. If you already have OA, then keeping your calves stretched and strong can make your knees feel better.
Quadriceps
The quadriceps is a large group of muscles located on the front of the thigh. They are responsible for extending the leg and they’re strongest muscles in the body.
The quadriceps is divided into four sections. All four parts attach to the knee cap through the patella tendon.
Rectus Femoris – Located in the middle of the thigh, this section of the quadriceps covers most of the other three sections of muscle (listed below). Along with knee extension, this muscle also helps flex the hip. It is attached to the ilium, or the top of the hip.
Vastus Lateralis – Located under the rectus femoris, this section of the quadriceps is attached to the femur and lies on the outside (lateral side) of the thigh.
Vastus Medialis – Located under the rectus femoris, this section of the quadriceps is attached to the femur and lies on the inside (medial side) of the thigh.
Vastus Intermedius – Located under the rectus femoris, this section of the quadriceps is attached to the femur and lies between the vastus medialis and vastus lateralis.
Since all four sections of the quadriceps attach themselves to the knee cap, these muscles play an important role in how the knee slides and glides. Injury of weakness can lead to or affect osteoarthritis of the knee.
Hamstrings
Hamstrings refer to the muscles located on the back of your thigh. These four muscles are responsible for flexing the knee, and three of the four help extend the hip. The hamstrings are comprised of the:
Semitendinosus: is located on the back of the thigh, on the inside of the body (medial aspect). This muscles helps straighten the hip and bend the knee. It also assists rotating the knee inward (medially).
Semimembranosus – is located on the back of the thigh, on the very inside of the leg. This muscle helps straighten the hip and bend the knee.
Biceps Femoris – is located on the back of the thigh, and has two parts:
- Long Head – attaches from the hip to the fibula and tibia. It is responsible for extending the hip and bending the knee. It also helps rotate the leg.
- Short Head – attaches from the femur to the fibula and tibia. It is responsible for bending the knee and rotating the leg.
Keeping the hamstrings flexible is important if you have osteoarthritis. Tight hamstrings will affect how your knee bends and straightens.
Knee Tendons
Tendons usually connect bones to muscles. Tendons, also called sinew, are tough bands of connective tissue made from collagen. The Patellar tendon is about 10cm in length and is flat and strong. It connects the Quadriceps muscle to the tibia, and passes along either side of the patella. It is divided into two distinct sections: